Thermal additive waterflooding method



-ADDITIVE BANK.

-TIIERMAL DRIVEv Sept 7,1965

:'T'na'sPl-Ehs :TEMPERATUREHOT WATER, :DRIVE WATER vSLUG .FIGB

TEMPERATURE R'ECQRDER NFLooDEDz" oRMATloN r C 'JQHNSCN, L Ew- "3,204,694 'THERMAL bmnvs umane mona Sepn 7, 1,965',l

EFFLUENT VOLUME (pv) FIG 5 INVENTORS CARL E. JOHNSOLJ.

LLN`P. TUDGE- ATORN'EY .02o if A c. JOHNSON, JR.. Eff-Ax. THERMAL v@1mm/5: wnmoomns monjf .Ssneet. ,esi

FIG. 6

*3.9 EFFLUENT .voLuMEj(pv) Augen; N evs mvEN-ros CA RL E. JOHNSON, JR.' ALLAN rups:

abandoned. v

in the ooding' duid.

.This invention relates to theeiciencyof assisted r 3,204,694- f s ADDmVE VATERFLOODING Carl E. Johnson, Jr.,

METHOD Filed ret. 19, 1964, ser. No. 346,008 l 9 Claims."(CL 1 66-11.)

Laguna Beach, and Allan P'. Tndge,"` 1 Fullerton, Calif., assignors to California Research Corporation, San Francisco, Calif.,y a corporationgnf improved methods of assisting the recovery of oil 'from oil-bearing formations, and more particularly, it relates to methods of using heat to improve*V 1 United safes; een 0f 'ood.' v Following the injection'of: the additivesolution,`

ctc.

made to increase the amount of oil recovered by mixing thickeners; bactcricides; chemical tracers; and other additives to a water to'od used in aiding oil recovery. The "1 usual method of additive ooding involves injecting an z 'maintaining substantially through the entire reservoir, at

recovery when additives are used' In most oilbearing formations, oil is tirst'rccov'ered by making use of formation pressures tol move'thef o il towards 'producing wells where it may be raised to the.l sur-face; t After the natural formation pressure has been depleted soit" is no longer etective in producing oiL: .A-

bank is pushed through the formatiorr.- This adsorption is duce the additive concentration in the additive-bank toa progressive deterioration of the additive in the bank by amount of additive solution into a formation through one .or more injection wells to establish `a bank or'zone of. -additive solution in the formation and then, following the injection of additive, injecting'untreated water-to move dtives in assisted recovery. ln order tov make additive flooding economically feasible, it is obviously necessary A that the value of the incremental oil recovered-be greatert the additive solution through the formationwhile re-A covering oil at one or more recovery 'wells.`

Many problems, however, have lretarded the use` of ad.- Y

than the additional cost of the additivefood. A number i. of factors inherent in additive ooding heretofore have vraised the cost of an additive ood so that 1its use hasv been prohibitive. Additives are generally compexorganic compounds which must-.be manufactured, thereby making their initial cost high. To compound, the problern of the initial cost, most of the additives arestronglytemporarily lost by adsorption. The action of adsorption not only removes th'e additive from solution temporarily,

butalsofcauses the additive to become more spread out or dispersed in the formation as it is transported across the formation by the. carrier water." Thus, if anadditi've bank of highoonc'entration isformed in a formation, the", 1.

L actionof adsorption quickly reduces 'the concentration to a. lower value. Therefore, unless a vcryvlarge amount of additive in inject-edinitially, the concentration will' soon- -f FIGURE. 1 shows Langmuir-type isotherms the influence of temperature and concentration on the adbe so low the additive flood will recover vno more oil than i sorption, theconcentration profile of additive in sohtltion 'of tlood water that mustbe 4injected into the formation' -producing well, and also an increase time before j any additional-oil, dueto the additive dood, is recovered.' To better appreciate the;present invention, it is neces f v"io- The present application Ais a continuation-.inlpart'of 2P' pllcatlon Serial No. 59,655, ledSeptember 3Q, 1960, now.k tltive= solution of a predetermined concentration is tive solution..f1'his zone is" initially at aconoentration bank' towards. producing well: f-Since almost alladdit'ives 1i equilibrium for'. given conditions ofV concentration and f various secondary recoverymethods are utilized. It is in l temperature in a given forma t io1't.fv ,"Ifherefore, as this general area that the method of the present invention is concerned, although -it is preferredto use the term fassisted recovery. which, .while including secondary recovery as known in the art, is not limited to secondary re-h covery, but mayal'so include primary'or tertiary', f development of the formation. f

u The mostwidely employed method of assisted recovery is water flooding. However,` even after a successful water flood, it is often found that 30% to 50% of the original crude oil remains in the formation. Efforts have been following fresh-drivewater. `The end effect of .this procem. isfto spread out the additive bank and to eventually rethrough the formation, eventually most of the additive can be desorbed and moved through the formation. How. v

y additive in the bank will remain at a high concentration ff through substantialy the entire reservoir, howeventhittA least adesi-red minimum concentration of additive in solu-` ,Y tion in the additive bankwhich involves generally the solution into the formation through one or more'injection wells to establish an additive zone inthe formation, and, following the injection of'the additive solution, injecting of fluid at a predetermined elevated-temperature to move 1 thefadditive zone through the formation and recovering Voil from one or more recovery wells;

- 'method of improving additive flooding by making'pred.

a conventional water ood. In addition,

will not travel through-the formation as quiclyvas the water ood, thus rcsuitingin an increase in the amountv in order to carry the additive'across the formation to the sary to understand the adsorption problem encountered in an additive ood.' In'any given additive ood, anadectedinto a formation tof set up azone or bank of addiwhich will recover more oil thanconventionaif-,water waterv is injected vinto the'form'ation to move theadditive..

are subject to` adsorption at solidsurfaces, the additive will tend to.- adsorb at the porous Y formation as the additive in most cases rapid land reversible and tends to reach bank moves; through the formation, additive'will-.be ad-Y sorbed from -the bank and subsequently desorbedby the concentrationA that-.will recover no more oil than a con- 'v'entional water ood.- If enough ushing water is forced ever, the solution is so dilute that the beneficial e'cct of the additive' o'od is lost. It is possible-to combat the injecting a large amount ofadditive'solution so that is not done due. to 'the prohibitive economics.

Y Briey, the present invention provides a methodof steps of determining the properties of-thc particular oilcj bearing formation to be tlooded, selecting an additive hav ng'prcdeterminable adsorption and thermal properties .i and, when used to flood the formation, will significantly increase the amount ofv oil recovered over a conventional 4water flood," preparing a solution, suspension or emulsion l of the additive-in a concentration effective in increasing "oil recovery from the formation, injecting the additive through the same or nearbyjnjection wells at east a slug It Vis an object of the present invention to provide a'.

ternnned temperature adjustments in either or boththe' t additive solution and the drivev water.

Further advantagesand'objectsv of the'invention will v become apparent from-the following detailed description read in view of the accompanying drawings which are a' i partofthisspecicatonandinwhich:;. r.

illustrating; Y

sorption of a typical additive at theintcrnal surfaces of.: i porous formation rock. .v -Y I FIGURE 2 isfa vertical section of an oil-bearing formation -and is usefulv in illustrating one embodiment of the invention.

FIGURE is a venten section of anon-bearing formai tio'ri and is useful in illustrating one embodiment of the v5 invention.'

FIGURE 4 is a-schematic diagram *illustrating appa- FIGURE 5shows curves obtained from additive doods.

FIGURE 6 showsv curves obtained from additive doods. 10

i FIGURE 7 shows curves obtained from additive hoods.

The amount of adsorptionjfor 'a' given additive used 'A rnwater ooding is primarily dependent 'on three variables.- These variables are the formation surface, the concentration of the additivein-solution and the temperature ".15

I of the solution when contacted with theforrnation. Refer:

ring to FIGURE Vl, adsorption isotherms at temperature Tntlow) and at'temperatureTn (high) Aare shown for a-representative additive which may be used in the meth- 1 9d .f the invention.- The term additive is meant to inl' v.2g

clude surface-active agents including cationics,- nonioni:s;,` anionics, and ampholytics, water thickeners, bactericides,

l chemical tracers, and any otheradditives to a''ood which have adsorptionisothetms generally similar tothose of lFIGURE l in, tbatthe adsorption-at the higher temf vv "'peratureis less ythan at some preselected-lower tempera- 'H TL is u sedto refer to the temperature of a given i ffl-formation in which an additive tlood'iscontemplatedA and -1TH is-used to represent the temperature of a heat bank 30 @which is to be established -in the given formation accord# y ing to theprese'nt "invention, it is evident by, examining the isotherms at TB and TI', in FIGURE l, that the weight ofadditive absorbed at the formation surface at'the contemplated injection concentration is significantly less 35 at- T'than for the same concentration at TL. Thus whenf; sideration must be given to the adsorptioncharacteristics selecting 'an additive in accordance with the invention, conlof the additive at different temperature levels. Any addi tive which has isotherms similar to thosel shown in FIG- 40 a URE l and which has the'herein-'described' thermal and l ed recovery flood according to the present invention.`

jventional water ood in all reservoirs, it is obvious that oil recovery properties is usable as an additive in Aan assist- Since it is well known in the art that not all additives will economically increase the recovery of oil over a conin selecting an additive for the tlood,- the first consideration must be to select a number of' additives having prop -Verties which will economically increase oil recovery in the particular reservoir under consideration. Themini'- 50 'A V`no`mically recovering oil is determined at this initial stage.

mum concentration of additive which is effective in ecoand, in addition, the maximum amount of additive which -can beadded to the solvent before gelling or precipitation occurs must be determined for the additives. These data can be' obtained by conventional laboratory methods including core flooding carried out under simulated reservoir conditions of pressure, temperature and oil saturation.'

After preliminarily selecting a number of additives with l desired recovery properties,- the adsorption properties of the additives at different temperatures must be determined. To find these "properties, tests are conducted in. the laboratory atvarious temperatures including at least the temperature'of the lformation V(TL) and at a temperhighest temperature which can economically be mainat-this temperature or the selection of TH maybe based i tained in a heat bank in the formation and the preselected if additives thermal' and adsorption properties determined f on the above-obtained laboratory data for a number of different additives at varie us temperatures and T3 selected 75 3,204,694v equal to the temperature where a given additive most promising adsorptive and thermal properties. It has been found that any increase in temperature of the heat bank over the formation temperature .is helpful in carrying out the invention. However, it is preferred to have atleast a 10. F. temperature gradient between the formation and the thermal drive water. 1 Thus, TH should 1 be at least 10 P'. greater than the formation temperature.. The upper limit of TB is governed by the economics o i maintaining the heat bank inthe formation and the temperature at which a given additive selected for the flood thermally `decomposes or precipitates.4 The' vconcentratio'n of the additivejin solution during theseadsorption testsfis at least-the minimum concentration which will produce increased oil recovery and preferablythe concentration vis the maximum concentration before gelling or precipitation occurs. Since it. is. well known that soine additives.changedrastically in solubility when subjected to increasedtemperatures, this thermal property must be 'al precipitation' :tcctu's-jat Tg; i vthen thisA additive must eliminatedfrom. consideration. l In addition, any additive .which thermally decomposes al g the'ex'pected Tg must: not be selected, for-the flood.- he Y v amount of adsorption-canhe determined by lconventional laboratory means', at dierent temperatures, and the additive with best adsorption'properti'es selected.. Here, "n: is 1 *i desirable that not only .the adsorption at T1, be relatively -low, but also that the increment in theamonnt adsorbed between TL and TH be large'.` The additive which has the largest increment, other properties being equal. (includingl re adsorption), should be selected for the examined and ifs ubsta'n low temperato ng the additive solution for injection into the formation, consideration must be given to vthe laboratory tests heretofore described, particularly with regard tothe minimum concentration etectve in recovering additional l -oil and tbemaximurn'amount of additive thatmay be, Vmixed with a given volume of water before gelling or" precipitation occurs. The present method permits the use of a smaller amount of additive than was heretofore possible. Although additives obviouslyvary in-properte;A it is generally expected that utilizing the method of the present invention, a successful additive ood can be aocomplished using between .02 pound/barrel of pon: space of the tlooded'formaton to 2 pounds/barrel of pore space In' one embodiment' of the in- Y venticin, this additive is mixedwith water in as concen F f -2 trated a solutionas possible, without causing gellingor precipitation, prior to injection into the formation. Mix# ing the additive in this manner reduces injection costs by lowerngthe volume of solution which must'be and it also provides for the establishment of a highly con centrated additive bank.V The additive solution, however, may be injected in'any volume inwhichtlie additive oont fall-below the minimum concexltl'n-` tion effectivein recovering increased oil. f"

5th reference to FIGURE 2, apparatm for injecting and recovering fluids from an earth formation is shown. Tne methods of `and apparatus for injecting liquids into a formation and recovering tiuids 'from a formation are well known inthe art and generally any of these may be utilized in the practice of the present invention. One form .of apparatus for injecting fluids into a formation 1 includes a tubing string 30. The tubing string 30 municates with the producing formation through appro- The discharge end of a conventional pump 34 is connectedto the other endof tubing. string 30'. .Tubing meansv 35 are provided for owng huid, suchas the additivesolution `to the pump 34. Heating means (not shownyare provided to increase the temperaure vof the injected fluids in accordance with the of the flooded formation.

l centration does no It has been found that'when an additive solution is njected into a formation which has a temperature greater than atmospheric temperature, the mannerinwhich the lected for a given flood does notadsorb ata particular l' formation surface at the there-existing temperature to the "extent that requires` that the additive solution be followed injection temperaturelof the additive solution,- which is the formation by the injection of atmospheric temperature mation while the other'fraction will be immediatelyad- .sorbed at tbe formation surface. Thus if there is a dis.

parity of greater than about .Fi between' the additive solution and the hotter formation, Splitting of theinjected z bank will result.v The reason for this phenomenon is not.

3,204,694 Y Y i vtion Aand the formation that -is controlling and not absolute temperature of the fonnation itself.- i t" ,-by a'heat bank, it has been found that if' the contemplated tive b'ank and tornovethe additive bank through the fort drive waten One'fracti'onwill move on out into the formation. AI 'he hot water following the additive baul: protion 'is greatly reduced.

'- known, but, because this splitting eect 'does occur in the'.

@additive bank, the concentration of the additive in som-- tion in the .bank is greatly reduced, usually' to Athe place where it is no longer effective inrecovering oil. Whilev "ther, fraction of additive immediately adsorbed'may be Y' desorbed by the later coldvdrive water, the bener'icial effect 15"? tirne .is lost; It has been discovered' that this undesirable effect can be avoided. One method of avoiding this result of the' concentrated slug of additive solution passing at 'one- I includes controlling therate ofthe injection 'ofthe addi tive solution so-that the solution takes advantage' of. the

the formation-at substantially atmospheric temperature.

' l temperature drive waterl maythen be injected to push the additive bank through the formation without theabovej desc'ribed splittinglocc'urring. Injection ratesvvary,ob viously, on the particular thermal properties of a given reservoir. The most desirable rate of injection of the additive solution to take advantage of the heat present in a `--particular reservoir can be determined in tests on coreA but rather as an `aid in its application, of calculatingan 4 injection ratewhereby the additive solution will enter the 1 v formation at substantially formation temperature is contained in an article entitled, How To Calculate Tempera- .ture Pro-les lin a `Water-Injection Well," by .l an Moss and Philipv D. White;` on page 174 of the Oil and Gas Ioumal,

- volume-57, No. 1l, March 9, 1959.

of the formation plus the calculated heat lost during injecv f the surface of the earth. However, thev invention is not w i Another method of injecting an additive'solution into a .50

tion. The hotadditive solution is then injected into the formation at any convenient-rate of injection. If the adsorption problem is not overly. severe then atmospheric.

l' temperature drive water maybe injected to for-ce the additive bank through the formation. Generally speaking,

formations in which this embodiment of the invention are t practiced are elevated temperature formations wherein advantage may be takenof the natural heat of thefonnature formation would normally be expected to be one in excess of 150 to 200' F., there are occasions where the additive-solution should alsobe heated prior to injection in lowerjtemperature reservoirs. This is especially true when the prevailing atmospheric temepmture is much lower than formation'ternperat'ure, as is the ca se in many 'tion in overcoming the adsorption problem. In this sense` it should be explained that although an elevated temperaf i slugZZ injected through well 17 which in turn has been northern areas. This is` true because we have found that,

it is the temperature -increment between the injected solunormally atmospheric temperature, is less than about 10 the.formaton and the additive bank thus established, at;

F. less than the temperature of the formation, the additive l solution -will split into two fractions as it moves out into the rock surfaces and returns it-to the additive bank. The concentration of -the additive bank thus remains high and the timerequired tomove the additive through the forma tio'n well 7 and one recovery well 8 is shown. The unnon bank s is established in formation 1 by mms of je'cting an additive solution from the surfaceof the earth we havefound that a temperature 'increaseof atleast 10' P. over the formation temperature is generally the smallest' throughvborehole 8 by means, for example, of a produc- .one recovery well 18. An additive bank 21 is established field practicea number of Wells probably would be used vIn accordance -with the preferred embodiment ofthe invention an additive solution bankis established in a for mation by injecting a .predetermined amount of additive solution through one or more injection wells intotthe for mation. 'Y After the additive solution has been injected into least a slugof hot water isinjected through the. sameor other vinjection wells to set up a hot zone behind the addi-l gressively desorbs additive which has been adsorbed-ou With reference to FIGURE 2;,.a vertical section of an I oil-bearing formation y1- -penetrated'by atleast. one injecfloodedportion of formationl is represented by numeral l 2, the underlying strata by 10 and theoverlying strata by 12. In one embodiment of the invention, an additivesolu- 5 through injection borehole 7 into the producing formation Il.v The additive is selected andthe solution prepared as heretofore'described'. The injection is accomplished byv f any conventional means and at any convenient rate. In this -embodiment of the invention, the solution is injected into Following the injection of the additive solution, a thermal drive zone 4 is'created by injecting hot water through bore fhole 7.. The optimum temperature of this dn've water depends on the variable previously discussed. However,

increment with which to successfully practice the inven ing formation 1. Products of the drive are recovered tion pump 29 and tubing 40. -The injection water may be heated by any conventional'means such as a boiler on v 'j dependent on the method of heatingvthe water. Drive l r 1 water could, for. instance, be heated by passing it through -t a heat bank established by underground combustion, either priorto or following thei injection of the additivesolution in formation 1.

An. alternative embodiment of the invention is illustrated in FIGURE 3. FIGURE 3 is a vertical section of an 'oil-bearing formation 25, overlying strata 26, underlying strata 27, at least one injection well 17 and atleast in formation 2S by injecting as heretofore described an i amount of additive solution. .The additive bank 21 is` moved -into the formation 25 by means of a hot water j followed by atmospheric temperature drive water 23 also Y injected through well 17. The portion of the formation which'has not yet been subjected to the additive flood is representedQby numeral 20. lt is recognized thatin actual as injection wells. The method of this invention therefore is not limited to anyunique arrangementl of wells.-y In this 'embodiment of the invention, a preselected ad-. A ditive is added to water or other suitable carrying agent l in the manner heretofore described and the solution is in t i t L- f jected into formation 2S from the surface 15 at substan tially atmospheric temperature and at any convenient in- 1 ff jection rate. Following the establishment of the additive vof h ot water should be initially injected atas high a tempcrature that can be maintained without causing thermal f1 v decomposition or precipitation of the additive used in the Y flooding solution. However, any temperatureincrease .in

the slug of water over the temperature of the formation is beneficial tothe tlood and may be utilized in thisA method. 'After the slug of hot water has been injected,

atmospheric temperature water may be used to move the ,Y additive bank 21 and hot water Islug 22 substantially i v through reservoir 25 to'oil production well 18 where the *'products of the drive are produced. I v

` While'the method of the invention has been described in asystem including an injection well and a production 1 wellit is clear that the method may also be advan-4 ftageously used ina. single well system. For example, it often desired to contact the'oil around a'rvell with an additive and then to back-flow this oil into the same well f'ffor production therefrom. Thus a cold additive solution, containing for example an additive which will'reduce the viscosity. of the oil, is injected into a well. Hot drive water or steam is injected for a predeterminable time v th'rough the same well to' move the additive solution out j into the formation without great loss by adsorption. The I l hot water, or steam injection is then stopped and the well .i

produced.

, A number of demonstrations have been made to show V the advantages of the method of the present invention. v The"apparatus used" in the demonstrations is shownschematically in FIGURE 4. A glass column was packedwith crushed sandstone 51 to simulate an oilproducing formation. Each of the ends 52 and 53 of the', glass column were filled for a short distance with small glass bead's.- The length of the glasscolumn was about 183 centimeters. About 161 centimeters of the column was packed with sand. When packed with sand the pore "olume of the sand pack in the glass column 50 was aboutV 80 cubic centimeters. Runs using both Berea sandstone and Torpedo sandstone were made. The porosity. of the packed sand in: glass column 5.0' was 39% and the perrneabili'ty was 1.47 Darcies when Berea sandstone was used and the porosity ofthe packed sand was l? to 40% v and the permeability about 2.74 Dai-cies when Torpedo sandstone was used..

One end 54 of the glass column 50 was prepared' with suitable tubing 55 and 56 for connection with a water injtion pump 57 and an additive solution injection pump 58. Valves 59 and 60 were provided to control the flow of water and additive solution into the glass column 50. The other end 61 of the glass column 50 was provided 'vnth a drain tube 62 and a means 63 for collecting fluid flowing therefrom. A movable electric furnace 64 was armngcd around the outside of the glass column 50' to simulate a heat bankin a producing formation. The

.. furnace was movable along the column. A thermocouple 65 connected to temperature recorder 66 provided tempcrature information along the column.

Using the demonstration apparatus shown in FIGURE 4 runs simulatingan additive fluid withoutbeneit of a heat bank could be made simply by not using the furnace.

when the furnace was heated and moved down the glass column it simulated the movement of a heat bank moving through the formation. Thus comparative datav were collectcd, which data' show theadvantages of the present invention.

where R represents the cellulose chain. The additive isa vwhite granular powder having no odor and is anionic.. c Low concentrations of vvthe additive in water produce a viscous solution., These viscous solutionsprovide limf pig-'was prepared. The solution was made in b rineyhaving 17 gm. of NaCl per liter. The glass column packed with a crushed Berea sandstone as describedabove was first pre- .pared by. saturating it with brine. The' additive solution 1 v'was then injected .into the column to set up an'additive vlas about .151 pore volume. After the additive bank additive' solution began to appear in the' eluent after..

, about one pore volume of brine had passed through the t. -glass'columm Additive continued t'o-be evidenced in `the eluent during injectionof the next half pore vvolume URE 5.l The' specific additive was CMC4-L manufac- Vtui'edby The Hercules Powder Company.. CMC4-L is a trademark of 'the Hercules Powder Company and is-a j carboxymethyl celluose polymer having the general proved oil recovery from `a petroleum-bearing formationl by providing a more favorable water-oil mobility ratio.

-Oil recovery is more eicient when. the viscosity of the pushing fluid approaches the viscosity of the pushedv oil. A CMC4-L solution having a viscosityV of 10.9 cp.:

bank in the column. The slug size of the additiveV bank was established-jin thecolumn, room'ternperaturc brine f (about 22 C.) was injected into the column to move the additive bank through the column while samples of the ellu'ent from the column were continuously taken. The viscosity ofthe ellluent was measured and is plotted as a function of; the etlluent volume in the curvesin FIG- URE 5.' The irst'pcak in the solid represents the additive in the effluent moved through the formation by room temperature brine. As is evident by the curve, the

of brine. The brine injection was continued. until about three total pore volumes of brine had passed through the -1 column. Itis apparent from the curve that very little' additional additive was carried through the glass column by the continual how of brine.

After the three pore' volumes of bn'ne had passed through the column, the furnace was positioned'at the entering end ofthe column, and the temperature o the furnace was raised to about 85 C. The furnace was started down the column after about 3.1 pore volumes of ellluent had emerged from the downstream end of the column. The furnace was moved slowly down the column toward the outlet: in a manner to simulate the movement of a heat bank through the formation. The furnace traveled at approximately of the uid velocity. The second peak in the solid curve of FIGURE 5 shows the additional additive in the etiiuent which was vde'sorbed from the porous sand and moved through the formation bythe injection of a small additional' amount of water. The additional additive is reilected by the peak effluent viscosity shown in the right-hand portion of the solid curve at 4.0 to 4.5 pore volumes eluent. The heat bank and the increased velocity solution apparently traveled together down .the column.

Demonstration II Tne method of the invention is even more dramatically demonstrated by a further demonstration carried out in 0.18 pore volume of ush water was injected. The fur-- n-ace was then placed atthe inletend of the column and the temperature raised to 85 C. The furnace was started after the 0.18 pore volume of drive water had been in with Torpedo sandstone.

Areached the downstream end ofthe column.

bank. 4The furnace was then slowly moved along the column *while flush water was injected The furnace traveled at approximately 83% of the speed of the fiuid. The dashed curve of-FIGURE 5 i illustrates the effect of the thermal bank moving through the formation with the additive bank. The additive bank f remained well defined and a great deal `more additive stayed in solution as' is witnessed 4by the greatly increased I ff viscosity of the effluent. 1 It is also apparent that the addi tive bank passed through the column when less than 1.5

pore volumes of etiluent were collected. is shown, -Aadditional flushing water did not bring-any additional additive through the column. This'demonstration shows 1 .clearly theimproved oil recovery lthat can be obtained Y 'using the method-of the present invention to both maintain maximum vadditive in solution-and to require the least amount of drive waterto-move the additive bank Athroughtlie formation.. Il: y -f Demonstration With reference now to FIGURE 6, the. results offa'nother demonstration are graphically shown'.- l A surfactant i was the Aadditive used in the demonstration illustrated in FIGURE 6. The additive was a California Research- Corporation' Special Alkane Sulfonate 10B R. The. stir-- f volume slug was injected into a column similar-to the'- factant was made by sulfonating the alkyl benzenes from the heavy fractionof an El Segundo polymer. The rev sulting material has a molecular weight of about 35 units i greater than the regular alkane..v The' empirial for.

I water. A slug'of thesolution in the amount of .154 pore llution was prepared Vand Van identical slug.l of surfactant factant. Y The umace was turned on and reached a teni-v I perature of' 80 C... The furnace was started after .I7 pore volume of distilled drive waterhad been injectedvolume was then injected into a glass column similar to the one shown in FIGURE 4. The column was packed After the slug was injected into the column, room tem -perature water (about 22 C.) was iniected to attempt to drive the surfactant through the formation.' As illustrated in the curve of FIGURE 6, a` very small concentration of surfactant emerged from the column at`from 1.2 to 1.5 eluent pore volumes. This amount repreof surfactant was held back'by adsorption since it'did not begin to emerge from the column until 1.2 pore volurnes' of effluent appeared. -Continued room temperature water injection produced no more surfactant.

After 1.21 pore volumes of eiuent had appeared at the concentration of thesurfactant was moved through the scribed herein may bemade to the method of this indownstream end of the.column the furnace was started at the upstream end of the column and moved along the column at .83 times the velocity. of the water moving through the column. The furnace temperature was 85 C. and produced a heat bank in the formation in accordance with the present invention.l

' Again' referring to FIGURE 6 the-second peak of the I curve illustrates the arrival of the surfactant bank at the fonate in the original injection slug was only .11 wt. percent. j Thus the concentration of the surfactant in the eiuenhwas almost twice the concentration of the surfactant in the original injected slug. This illustrates that a heat bank following the additive bank can actually cause the concentration of the additive in the bank to' exceed even the concentration of additive in the original slug. VThis is obviously of a great advantage in oil 'recoverysince the greater concentration of the -ff- The slug of the surfactant was followed by--roomft'empe'ra I the method of thepresent invention both in maintainadditive reaching the oil, Vthe vbetter the recovery will lie. Y

" Demonstration IV- Referring. now to FIGURE 7 the results of another 'demonstration are graphically shown by a pair of curves. A surfactantsoiutou was prepared using Ninol 1281. Ninol 1281 is a trademark of the Stephan Chemical Cornpany, Maywood, New-Jersey. Ninol 1281 is nonionic. aridl is a fatty acid alkylamide with the empirical foi.'-

mula

n A .10 percent -by Weighbconcentration solution of the surfactant wasprepared in distilled-watch and -a' .15. porc one shown in FIGURE 4' lled with Torpedo sandstone.

yture (about 22 C.) distilled water. Samples ofthe effluent were collected and analyzed. The solid in FIGURE 7 illustrates the concentration ofthe snrfactant in the etliuent from-the column. 1 Y

AFor comparative purposes anidentical surfactant s- '1.

was injected into the upstream end of an identically pirepared column.. Drive water wasvinjected behind the sur 1;

into the column. n The heat bank was Amoved down the I i column at about .8O times the velocity ofthe water travel- .f ing through the column.' The furnace reached the end of the column at approximately 1.43 pore volumes euent. The dashed curve in FIGURE 7 shows theconocn- .tration of the surfactant versusthe etuent volume. ,Aais apparent by comparing the two curves, a muchhigher formation using the heat bank in accordance witlithe invent1 on. Also much less water was required to move: n :she additive solution through the formation using the ank. 1v

The above demonstrations illustratethe'advantages of.v ,1

ing maximum additivein solution and in requiring the least amount of drive -water to move the additive bank through the solution.

It is apparent that modifications other than those de vv ei'ition without departing from the inventive concept. It isintended .that the invention embrace all equivalents y' within the scope of the appended claims. We claim: 1. The method `of improving oil recovery from a petroleum-bearing formation which comprises determining the formation temperature, mixing au additive with preselected thermal. adsorption, and recovery properties with a liquid, said additive selected from the group consisting of nonionic surface active agents, anionic surface active agents and water thickeners, injecting said liquid containing said additive into said formation, following said liquid containing said additive injecting. a hot drive liquid into said formation at a'tcmperature higher thai: said formation temperature yand the temperature of said liquid vcontaining said additive to create a temperature gradient of at least about 10 F. between said drive liquid andy l said liquid containing saidadditive,4 continuing the in- I jection of said drive liquid to force said liquid containing .said additive out into. said formation and recovering-oil..

from said formation through a well. 2. The method of'improving oil recovery from a pd i gradient is at least about 60 C.' i

formation temperature, mixing an additive with preselected thermal, adsorption, andrecovery properties with a liquid, said additive selected from the group consisting. of nonionic surface active agents, anionic surface active agents andr water thickeners, injecting saidliquid corrtaining saidadditive into said formation, following said liquid containing said additive injecting a hot drive liquidV K-Yinto said formation at a temperaturehigher than said formation' temperature and the temperature of said liquid containing said additive to create a temperature gradient f between said drive .liquid and s'aid liquid containing .st-id iadditive, continuing the injection of'said drive liquid t':

i force said liquid containingsaidadditive substantially' 'i through said .formation toward a producing well and rel covering'oil from said formation through said producing :11,3.. The'methodtof claim 2 where thesaid temperature gradient is vat least about IOF. 1

4. The method of claim 2' where d temperature troleum-bearing formation .which comprises determining 4 said'additive at substantially atmospheric temperature, it.'

jecting between 0.l and 0.6 pore-volume of drive liquid into said formation at a temperature at least 10 F. great-V l from a' petroleum-bearing formation penetrated by at least 5. 'Ihemethod of improving oil recoveryfrom ape- Y troleum-bearing formation which comprises determining said formation temperature, mixing an additive having pretermined thermal, adsorptive and oil recovery properties with a liquid,` said additive selected frornthe group consisting of nonionic surface active agents, anionic surin an" amount between 0.1 and 0.6' pore. volume of said formation injected into said formation at" a temperature higher than said formation temperature to 'create a temperature gradient between said'drive liquid and said liquid containing said additive, said drive liquid having a temperature highenough to maintain said `temperature gradient after heat exchange with said additive liquid, fol- Y lowing said drive liquid injecting water into said formation at substantially atmospheric temperature to substantially move said additive bank and Asaid drive liquid through said formation and recovering oil from said formation.

6. The method of claim S wherein the additive is con- Y tained in the liquid in anV amount betwen .0?. pound per barrel of formation pore space and 2 pounds per barrel of formation pore space, there being sufficient liquid to.A prevent gelling or precipitation of said additive, and the temperature gradient between the drive liquid and the said liquid containing said additive is at leastv 10 F.

7. The method of improving oil recovery from a. petroleum-bearing formation,` said formation having a one injection well and one recoverjmvell, said formationlShaving a known temperature comprising establishing in Vsaid formation .adjacent said injection wellxa solution. Y

'containing an additive, said additive seiected fromlhe .1j g group consisting of nonionic'surface active agents, anionic lsurface active agents and water4 thickeners, -said additive I being-less adsorbed at said formation surfaoe'at temperature TH than at temperature TL, whereTB is a tempera- 'ture at least` 10"v F. higher thanl said'formation tempera` ture and TL. is the temperature of said petroleum-bearing formation, injecting adrive liquid into said formation vtive agents, anionic surface active agents and water thickvcuers, injecting into said formation a liquid containing through said injection .well to move said additive solution out-into said formation, said drive liquid having a tempernature at least -equal to TH, continuing the injection of saidl drive liquid' to force said additive solution substantially f through said formation and recoveringY petroleum from said formation through said recovery well.

9. In a method ofl improving the recovery of oil from a petroleum-bearing formation 'which method includes i mation, theimprovement comprising selectingan additive from the group consisting-of nonionic surface active agents, anionic surface active agents. and water thickfeners for use in forming an additive 'solution'fcr injection through an injection well to form an additive solution bank in4 a formation and injecting a drive liquid into said formation through said injection'wellfto move said additive solution bank through said formation, said drive liquid having av temperature of at leastabout 1'0"- F.

known temperature comprising selecting an additiveV additive being less adsorbed at said formation surface at a temperature above -said known formation temperature than at-said formation temperature, said additive selected from the group consisting of noni'onic surface ao 'which will increase oil recovery-from said formation, saidhigher than said formation temperature andthe temperature of the additive solution to establish a temperature gradient between-said drive liquid and the additive solution bank in said formation.

v. "eferencesCit'edbytheExaminer ,Y Y

vUNITED STATES PATENsz,a13,583 11/ 57 4Mm e: a1. 16s- 11 2,903,065. 9/59, Holbrook eral -166-9 3,115,929 l2/63 Emery- 16s- 11- 3,153,448

-10/ 64 Dew et a1. 16s- 11 X BENJAMIN Haast-1, Primary Emma.. CHARLES E. ocoNNnLt, Examiner. 

9. IN A METHOD OF IMPROVING THE RECOVERY OF OIL FROM A PETROLEUM-BEARING FORMATION WHICH METHOD INCLUDES THE STEP OF INJECTING AN ADDITIVE SOLUTION THROUGH ANN INJECTION WELL TO ESTABLISH AN ADDITIVE SOLUTION BANK IN THE FORMATION, THE IMPROVEMENT COMPRISING SELECTING AN ADDITIVE FROM THE GROUP CONSISTING OF NONIONIC SURFACE ACTIVE AGENTS, ANIONIC SURFACE ACTIVE AGENTS AND WATER THICKENERS FOR USE IN FORMING AN ADDITIVE SOLUTION FOR INJECTION THROUGH AN INJECTION WELL TO FORM AN ADDITIVE SOLUTION BANK IN A FORMATION AND INJECTING A DRIVE LIQUID INTO SAID FORMAMTION THROUGH SAID INJECTION WELL TO MOVE SAID ADDITIVE SOLUTION BANK THROUGH SAID FORMATION, SAID DRIVE LIQUID HAVING A TEMPERATURE OF AT LEAST ABOUT 10*F. HIGHER THAN SAID FORMATION TEMPERATURE AND THE TEMPERATURE OF THE ADDITIVE SOLUTION TO ESTABLISH A TEMPERATURE GRADIENT BETWEEN SAID DRIVE LIQUID AND THE ADDITIVE SOLUTION BANK IN SAID FORMATION. 